<?php
/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Db
 * @subpackage Adapter
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Db2.php 24593 2012-01-05 20:35:02Z matthew $
 */
/**
 *
 * @see Zend_Db_Adapter_Pdo_Ibm
 */
require_once 'Zend/Db/Adapter/Pdo/Ibm.php';
/**
 *
 * @see Zend_Db_Statement_Pdo_Ibm
 */
require_once 'Zend/Db/Statement/Pdo/Ibm.php';

/**
 *
 * @category Zend
 * @package Zend_Db
 * @subpackage Adapter
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
class Zend_Db_Adapter_Pdo_Ibm_Db2 {

    /**
     *
     * @var Zend_Db_Adapter_Abstract
     */
    protected $_adapter = null;

    /**
     * Construct the data server class.
     * It will be used to generate non-generic SQL
     * for a particular data server
     * @param Zend_Db_Adapter_Abstract $adapter
     */
    public function __construct ($adapter) {
        $this -> _adapter = $adapter;
    }

    /**
     * Returns a list of the tables in the database.
     * @return array
     */
    public function listTables () {
        $sql = "SELECT tabname " . "FROM SYSCAT.TABLES ";
        return $this -> _adapter -> fetchCol ($sql);
    }

    /**
     * DB2 catalog lookup for describe table
     * @param string $tableName
     * @param string $schemaName OPTIONAL
     * @return array
     */
    public function describeTable ($tableName, $schemaName = null) {
        $sql = "SELECT DISTINCT c.tabschema, c.tabname, c.colname, c.colno,
                c.typename, c.default, c.nulls, c.length, c.scale,
                c.identity, tc.type AS tabconsttype, k.colseq
                FROM syscat.columns c
                LEFT JOIN (syscat.keycoluse k JOIN syscat.tabconst tc
                 ON (k.tabschema = tc.tabschema
                   AND k.tabname = tc.tabname
                   AND tc.type = 'P'))
                 ON (c.tabschema = k.tabschema
                 AND c.tabname = k.tabname
                 AND c.colname = k.colname)
            WHERE " . $this -> _adapter -> quoteInto ('UPPER(c.tabname) = UPPER(?)', $tableName);
        if ($schemaName) {
            $sql .= $this -> _adapter -> quoteInto (' AND UPPER(c.tabschema) = UPPER(?)', $schemaName);
        }
        $sql .= " ORDER BY c.colno";
        $desc = array();
        $stmt = $this -> _adapter -> query ($sql);
        /**
         * To avoid case issues, fetch using FETCH_NUM
         */
        $result = $stmt -> fetchAll (Zend_Db::FETCH_NUM);
        /**
         * The ordering of columns is defined by the query so we can map
         * to variables to improve readability
         */
        $tabschema = 0;
        $tabname = 1;
        $colname = 2;
        $colno = 3;
        $typename = 4;
        $default = 5;
        $nulls = 6;
        $length = 7;
        $scale = 8;
        $identityCol = 9;
        $tabconstype = 10;
        $colseq = 11;
        foreach ($result as $key => $row) {
            list ($primary, $primaryPosition, $identity) = array(false, null, false);
            if ($row[$tabconstype] == 'P') {
                $primary = true;
                $primaryPosition = $row[$colseq];
            }
            /**
             * In IBM DB2, an column can be IDENTITY
             * even if it is not part of the PRIMARY KEY.
             */
            if ($row[$identityCol] == 'Y') {
                $identity = true;
            }
            $desc[$this -> _adapter -> foldCase ($row[$colname])] = array('SCHEMA_NAME' => $this -> _adapter -> foldCase ($row[$tabschema]), 'TABLE_NAME' => $this -> _adapter -> foldCase ($row[$tabname]), 'COLUMN_NAME' => $this -> _adapter -> foldCase ($row[$colname]), 'COLUMN_POSITION' => $row[$colno] + 1, 'DATA_TYPE' => $row[$typename], 'DEFAULT' => $row[$default], 'NULLABLE' => (bool) ($row[$nulls] == 'Y'), 'LENGTH' => $row[$length], 'SCALE' => $row[$scale], 'PRECISION' => ($row[$typename] == 'DECIMAL' ? $row[$length] : 0), 'UNSIGNED' => false, 'PRIMARY' => $primary, 'PRIMARY_POSITION' => $primaryPosition, 'IDENTITY' => $identity);
        }
        return $desc;
    }

    /**
     * Adds a DB2-specific LIMIT clause to the SELECT statement.
     * @param string $sql
     * @param integer $count
     * @param integer $offset OPTIONAL
     * @throws Zend_Db_Adapter_Exception
     * @return string
     */
    public function limit ($sql, $count, $offset = 0) {
        $count = intval ($count);
        if ($count < 0) {
            /**
             *
             * @see Zend_Db_Adapter_Exception
             */
            require_once 'Zend/Db/Adapter/Exception.php';
            throw new Zend_Db_Adapter_Exception ("LIMIT argument count=$count is not valid");
        } else {
            $offset = intval ($offset);
            if ($offset < 0) {
                /**
                 *
                 * @see Zend_Db_Adapter_Exception
                 */
                require_once 'Zend/Db/Adapter/Exception.php';
                throw new Zend_Db_Adapter_Exception ("LIMIT argument offset=$offset is not valid");
            }
            if ($offset == 0 && $count > 0) {
                $limit_sql = $sql . " FETCH FIRST $count ROWS ONLY";
                return $limit_sql;
            }
            /**
             * DB2 does not implement the LIMIT clause as some RDBMS do.
             * We have to simulate it with subqueries and ROWNUM.
             * Unfortunately because we use the column wildcard "*",
             * this puts an extra column into the query result set.
             */
            $limit_sql = "SELECT z2.*
              FROM (
                  SELECT ROW_NUMBER() OVER() AS \"ZEND_DB_ROWNUM\", z1.*
                  FROM (
                      " . $sql . "
                  ) z1
              ) z2
              WHERE z2.zend_db_rownum BETWEEN " . ($offset + 1) . " AND " . ($offset + $count);
        }
        return $limit_sql;
    }

    /**
     * DB2-specific last sequence id
     * @param string $sequenceName
     * @return integer
     */
    public function lastSequenceId ($sequenceName) {
        $sql = 'SELECT PREVVAL FOR ' . $this -> _adapter -> quoteIdentifier ($sequenceName) . ' AS VAL FROM SYSIBM.SYSDUMMY1';
        $value = $this -> _adapter -> fetchOne ($sql);
        return $value;
    }

    /**
     * DB2-specific sequence id value
     * @param string $sequenceName
     * @return integer
     */
    public function nextSequenceId ($sequenceName) {
        $sql = 'SELECT NEXTVAL FOR ' . $this -> _adapter -> quoteIdentifier ($sequenceName) . ' AS VAL FROM SYSIBM.SYSDUMMY1';
        $value = $this -> _adapter -> fetchOne ($sql);
        return $value;
    }

}
